As a result of continues changes in linux kernel, new system calls are added all the time. In version 4.9, to support a new system call we need to change a source assembly file (arch/arm/kernel/calls.S) and to add the source file with SYSCALL_DEFINEx macro and the function declaration

From version 4.10 it is done by editing a simple text file in arch/arm/tools/syscall.tbl

If you add a new system call , you need to edit the file and declare which format is supported (eabi / oabi / common)